A 42-year-old woman with a 5-year history of asthma and chronic nasal obstruction presents with recurrent episodes of acute rhinosinusitis. Nasal endoscopy reveals multiple pale polyps bilaterally. She reports that her symptoms worsen with aspirin and NSAIDs. High-resolution CT PNS shows bilateral ethmoid and maxillary sinus opacification with polypoidal masses. Which of the following is the most appropriate first-line pharmacological management?